BRP Rotax 125 JUNIOR MAX evo User manual

OPERATOR‘S
MANUAL
125 SENIOR MAX EVO
125 JUNIOR MAX EVO
125 MINI MAX EVO
125 MICRO MAX EVO
KART ED. 03/2021
PART NO. 297732
ROTAX-KART.COM

Follow us:BRP-Rotax GmbH & Co KG
Rotaxstraße 1
4623 Gunskirchen, Austria
T: + 43 7246 601 - 0
F: + 43 7246 6370
www.rotax-kart.com
GENERAL INFORMATION
BRP-ROTAX RECOMMENDS PRODUCTS
OF THE FOLLOWING COMPANIES:

Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo Content
Page 1
Edition: March 01 2021
Table of Content
Chapter INTRO – GENERAL INFORMATION
Chapter 1 – Technical Description
Chapter 2 – Engine
Chapter 3 – Engine calibration
Chapter 4 – Engine operation
Chapter 5 – Preservation and transport
BRP-Rotax
Operators Manual

Page 2
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo
NOTES
BRP-Rotax
Operators Manual

BRP-Rotax
Operators Manual
Chapter: INTRO
GENERAL INFORMATION
Preface Before operating the engine, read the Operators Manual carefully.
If any passages of the Manual are not clearly understood or if you have questions, please
contact an authorized Distribution or Service Center for ROTAX®-kart engines.
This document and all technical data and procedures therein are property of BRP-Rotax
GmbH & Co KG and based on the state of knowledge at the time of publication The
Manual has been drawn up to the best of our knowledge. However, excluding any liability.
We reserve all rights including technical modification and possibility of errors. Reprinting,
translation or copies in whole or in part, are authorized only after written permission by
BRP-Rotax GmbH & Co KG.
BRP-Rotax GmbH & Co KG reserves the right at any time to discontinue or change
specifications, prices, designs, features, models or equipment without incurring obligation.
Engine performance may vary depending on, among other things, general conditions,
ambient temperature and altitude.
Contents This Operators Manual contains instructions about how to operate the ROTAX®-Engine
Type 125 MAX evo, 125 Junior MAX evo, 125 Mini MAX evo and 125 Micro MAX evo.
Safety Messages The types of safety messages, what they look like and how they are used in this guide are
explained as follows: The safety alert symbol indicates a potential injury hazard.
mWARNING
Indicates a potential hazard, if not avoided, could result in serious injury or
death.
mCAUTION
Indicates a hazard situation which, if not avoided, could result in minor or
moderate injury.
ATTENTION
Indicates an instruction which, if not followed, could severely damage vehicle
components or other property.
ENVIRONMENTAL NOTE
Environmental notes give you tips on environmental protection.
NOTE
Indicates supplementary information which may be needed to fully complete or
understand an instruction.
✔Denotes a checking operation
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo INTRO
Page 1
Edition: March 01 2021

BRP-Rotax
Operators Manual
TIP This information gives you additional advice and tips
mWARNING
This vehicle may exceed the performance of other vehicles you may have ridden. Take
time to familiarize yourself with your new vehicle.
______________________________________________________
INTRO
Page 2
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
Operators Manual
Chapter: 1
TECHNICAL DESCRIPTION
TOPICS IN THIS CHAPTER
Design of the ROTAX engine types 125 MAX evo, Junior MAX evo, Mini MAX evo and Micro MAX
evo ..........................................................................................................................................................2
General ................................................................................................................................................2
Cooling circuit .......................................................................................................................................2
Balance shaft ........................................................................................................................................2
Ignition unit ...........................................................................................................................................2
Electric starter.......................................................................................................................................2
Electro pneumatically exhaust timing control (125 MAX only)....................................................................3
Intake silencer.......................................................................................................................................3
Exhaust system.....................................................................................................................................3
Fuel pump ............................................................................................................................................3
Carburetor ............................................................................................................................................3
Centrifugal clutch ..................................................................................................................................4
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 1
Page 1
Edition: March 01 2021

BRP-Rotax
Operators Manual
DESIGN OF THE ROTAX ENGINE TYPES 125 MAX EVO, JUNIOR MAX
EVO, MINI MAX EVO AND MICRO MAX EVO
GENERAL
The Rotax 125 MAX evo engine is a single cylinder two stroke engine with reed valve con-
trolled inlet and 125 cm3displacement. Mixture lubrication is achieved by adding oil to the
gasoline in a specified mixing ratio.
________________________________________________________________
COOLING CIRCUIT
The coolant is pumped from the radiator to the water pump which is driven by the clutch
shaft. The water pump conveys the coolant through cylinder and the cylinder head back to
the radiator.
The cooling circuit is equipped with a thermostat (opening point 45 °C / 113 °F). It assures
that the engine reaches its operating temperature quickly and keeps it at a relatively con-
stant level.
The thermostat is integrated in the cylinder head cover.
________________________________________________________________
BALANCE SHAFT
The balance shaft rotates counter-wise to the crankshaft to reduce engine vibration.
________________________________________________________________
IGNITION UNIT
The control of the ignition system is exercised by the ECU (Engine Control Unit). To calcu-
late the ignition timing, an engine speed sensor is needed, which is installed on the bottom
of the engine housing. There is no manual adjustment of the ignition system necessary
and/or possible.
Even if the engine is stopped, the ignition system consumes current. After use, always set
the combination switch to position "OFF", to avoid deep discharge of the battery.
________________________________________________________________
ELECTRIC STARTER
By pressing the "START" button, the circuit between the battery and the electric starter will
be closed by a relay. The electric starter drives the starter gear on the crankshaft via an in-
termediate gear with free wheeling, until the engine starts to run. An automatic switch re-
set from "START" to "ON" is integrated.
________________________________________________________________
1
Page 2
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
Operators Manual
ELECTRO PNEUMATICALLY EXHAUST TIMING CONTROL (125 MAX ONLY)
The engine type 125 MAX evo is equipped with an electro-pneumatic exhaust control. The
E-RAVE (Electronic ROTAX Adjustable Variable Exhaust) system is controlled by an elec-
tro-pneumatic valve via the ECU. The vacuum required is provided by the engine
crankcase.
If the engine is running at idle speed or below the opening point of the E-RAVE system
(between approximately 8000-9000 rpm) the exhaust valve is closed. With the engine run-
ning, it closes or opens the electro-pneumatic valve of the exhaust depending on the
speed and, therefore it provides optimum performance characteristics.
________________________________________________________________
INTAKE SILENCER
The intake silencer incorporates an air filter to clean the intake air. The intake silencer has
been designed for optimum reduction of air intake noise level and represents a tuned sys-
tem with the engine.
The air filter consists of several layers and has been optimized in the area of air passage
and filter to work more effectively. If soiled or during engine maintenance work, clean the
filter with biodegradable products.
________________________________________________________________
EXHAUST SYSTEM
The exhaust system is designed as resonance system with an after-muffler and repre-
sents a tuned system with engine.
________________________________________________________________
FUEL PUMP
The fuel pump is actuated by the pulsating pressure changes in the crankcase and the
pump transfers the fuel from the fuel tank to the carburetor.
An inline fuel filter (between fuel tank and fuel pump) keeps foreign particles from entering
the fuel pump or the carburetor, respectively.
________________________________________________________________
CARBURETOR
The carburetor (DELL’ORTO VHSB 34) is a slide type carburetor with float system. The
standard main jet is suitable for almost all operating conditions. For extreme operating
conditions, the main jet size must be adjusted to the actual conditions according to this
manual.
________________________________________________________________
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 1
Page 3
Edition: March 01 2021

BRP-Rotax
Operators Manual
CENTRIFUGAL CLUTCH
The engine is equipped with a centrifugal clutch operating in an oil bath. This clutch sepa-
rates the engine from the gearbox at less than 2.500 rpm. Only at an engine speed of ap-
prox. 4.000 rpm. the centrifugal clutch is completely engaged.
________________________________________________________________
1
Page 4
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
Operators Manual
Chapter: 2
ENGINE
TOPICS IN THIS CHAPTER
Operating fluids and battery....................................................................................................................2
Coolant.................................................................................................................................................2
Battery..................................................................................................................................................2
Battery charging unit..............................................................................................................................4
Fuel......................................................................................................................................................5
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 2
Page 1
Edition: March 01 2021

BRP-Rotax
Operators Manual
OPERATING FLUIDS AND BATTERY
See also table “important information (summary)” in Chapter 5.
COOLANT
Use only distilled water as engine coolant. If the kart is stored below the freezing tempera-
ture of water, make sure to drain the water from the cooling radiator and engine
completely.
Step Procedure
1Open radiator cap and fill the system with coolant.
Small radiator: approx. 0.52 liter / 0.137 gal for the complete cooling system
Big radiator: approx. 0.7 liter / 0.185 gal for the complete cooling system
2Close radiator cap.
ATTENTION
Observe the storage conditions.
Storage below the freezing temperature of water could lead to a damage of the cooling
system and the engine.
ATTENTION
Exceeding the engine temperature could lead to serious engine failure.
The engine temperature should not exceed 85 °C / 185 °F.
______________________________________________________
BATTERY
See Fig. Pos. 1: Charging connector, TYPICAL.
The power for the ignition unit and electric starter is only supplied from the battery. With a
fully charged battery of 12 V and 6.5 Ah, the engine can be started approximately one hun-
dred times and operated over a period of approximately five hours. With the battery volt-
age decreasing to approximately 11 V the point will be reached when the battery voltage
is too low to generate a spark for ignition.
ATTENTION
The lifespan of the battery will be drastically reduced by exhausting the battery
completely.
Fully re-charge the battery before and after any operation of the kart.
NOTE
It is recommended to always carry a charged spare battery. The installed battery
should be replaced with a fully charged battery before it is completely exhausted.
2
Page 2
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
Operators Manual
NOTE
If the spark plug is removed, to check if the battery still generates a spark, consid-
er the following: with the spark plug removed it is easier for the electric starter to
crank the engine, which reduces current absorption of the electric starter, result-
ing in battery voltage adequate to generate a spark. If the spark plug is fitted
again, it may happen that the engine does not start.
NOTE
To charge a battery, the battery charging unit specified by ROTAX® and available
as an accessory should be utilized (battery charger part no. 265148). When using
the lithium battery available as spare part, the battery charger Optimate Lithium
(part no. 581325) is mandatory.
NOTE
To be able to use the battery charger in your home country, please contact your
nearest authorized ROTAX® distributor or one of their ROTAX® Service Centers
to receive an adapter plug or adapter cable, respectively.
NOTE
This battery charger will switch over automatically to maintenance charge as soon
as the target voltage is reached. Therefore overcharging with the result of ruining
the battery will be impossible.
ATTENTION
Use of any other battery charger can impair the battery life or may ruin the battery.
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 2
Page 3
Edition: March 01 2021

BRP-Rotax
Operators Manual
BATTERY CHARGING UNIT
When charging the battery take note of the following:
Step Procedure
1Connect battery charger to the charging connector (pos. 1).
Figure 2.1: Pos. 1: Charging connector, TYPICAL
Step Procedure
2 Connect the battery charging unit on 110-230V, 50 - 60Hz power supply.
During the charging procedure, the charge indicating lamp will light up red.
3At completion of the charging process, the control lamp will change to
green, but the charging current will remain, thus warranting a fully charged
battery.
4 The charging time amounts to approx. 12 hours.
NOTE
The battery charger may be connected to the battery for a longer period, as the
battery takes just the current required to be fully charged.
NOTE
A non-extinguishing red control lamp, even after 24 hours of charging, indicates
that the charging capacity of the battery is diminishing.
NOTE
A red/green blinking of the charging control lamp indicates transition from main
charging to additional charging and does not signal a faulty battery charger.
2
Page 4
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
Operators Manual
Step Procedure
5Unplug power supply to battery charging unit.
6Remove output wires of the battery charger from the battery.
7The battery is ready again for use.
ATTENTION
In addition to these directives, follow the advice of the battery charging unit
manufacturer.
NOTE
When the battery is charged while not mounted on the kart, use the connector ca-
ble (part no. 266022). If needed, contact your authorized distributor or one of their
ROTAX® Service Centers.
The charging condition of the battery can be estimated by using a commercially available
measuring instrument.
______________________________________________________
FUEL
For engine operation, a mixture of unleaded gasoline of at least ROZ min. 95 / 91 (RON
+MON) / 2 and fully synthetic two-stroke oil, mixed at ratio 1: 50 (2% oil) has to be used.
ATTENTION
Carry out a correct running-in procedure.
See Chapter 4 section: Running-in procedure for the engine.
mWARNING
Non-compliance can result in serious injuries or death!
When mixing fuel and fuelling do not smoke or allow open fire. Gasoline is highly flam-
mable and explosive under certain conditions.
mWARNING
Non-compliance can result in serious injuries or death!
Never perform mixing and fuelling in closed rooms, handle fuel in well ventilated areas
only.
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 2
Page 5
Edition: March 01 2021

BRP-Rotax
Operators Manual
mWARNING
Non-compliance can result in serious injuries or death!
Fuel the kart only when engine is not running and the combination switch is at OFF
position.
mWARNING
Risk of fire and explosion!
Make sure that fuel will not splash onto hot engine components or equipment.Always
wipe off any fuel spillage from the vehicle.
mWARNING
Non-compliance can result in serious injuries or death!
Pay attention to the safety advice of the kart manufacturer.
ATTENTION
Possible engine trouble!
Too much oil in the fuel mixture (more than 2%) could lead to engine trouble (e.g. coking
of the exhaust valve, piston ring sticking).
ATTENTION
Possible engine blow-up!
Insufficient amount of oil in the fuel mixture (less than 2%) could result in e.g. piston
seizure.
ATTENTION
Engine damage and damage to the intake system may occur.
Do not try any different sorts of fuel.
ATTENTION
Before each fuelling, shake fuel container well to ensure adequate mixing of the gaso-
line with the oil.
ATTENTION
Ensure that no contamination enters the fuel tank and the carburetor.
ATTENTION
Unleaded fuel has a limited storage life.
Store only the quantity of fuel in a container which will be needed in the near future.
2
Page 6
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo

BRP-Rotax
Operators Manual
ENVIRONMENTAL NOTE
Don’t spill fuel. Absorb spilled fuel with appropriate drying agent and ensure ecological
disposal.
______________________________________________________
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 2
Page 7
Edition: March 01 2021

Page 8
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo
NOTES
BRP-Rotax
Operators Manual

BRP-Rotax
Operators Manual
Chapter: 3
ENGINE CALIBRATION
TOPICS IN THIS CHAPTER
ENGINE CALIBRATION............................................................................................................................2
Run-in procedure ..................................................................................................................................2
Performance graphs ..............................................................................................................................2
Carburetor calibration ............................................................................................................................4
Automatic-set-up...................................................................................................................................5
Manual set-up .......................................................................................................................................8
Change of the carburetor main jet.........................................................................................................12
Selection of the transmission ratio ........................................................................................................15
Exchange of the clutch drum with chain sprocket fitted ...........................................................................17
Changing or renewal of the chain sprocket on the clutch drum ................................................................19
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo 3
Page 1
Edition: March 01 2021

BRP-Rotax
Operators Manual
ENGINE CALIBRATION
RUN-IN PROCEDURE
mWARNING
Non-compliance may result in serious injuries or death!
Running-in has to be done with a “long” gear ratio and a rich main jet (2 sizes bigger
than the recommended main jet based on altitude and temperature.
ATTENTION
For the first 10 liters of fuel use a mixing ratio of 1:33 (= 3% or 0.3 liter oil per 10 liters of
fuel).
NOTE
BRP-Rotax recommends to use XPS Kart - Tec oil.
Step Procedure
1 15 min. up to 10.000 rpm.
15 min. up to 12.000 rpm.
15 min. full load.
2 Reduce the main jet size step by step (e.g. 172 - 170 - 168 ...).
NOTE
Make sure that the coolant temperature reaches a minimum of 55 °C (130 °F).
At cold ambient temperature radiator needs to get partly covered by tape.
PERFORMANCE GRAPHS
In this diagram, the different performance characteristics of the MAX engines are shown.
The vertical Y-axis shows the power in kilowatts (kW). The horizontal X-axis shows the ro-
tational speed in revolutions per minute (rpm).
For more information, please check the performance data sheets on www.rotax-kart.com.
3
Page 2
Edition: March 01 2021
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo